Transcript for Behind the Diplomatic Possibilities With Syria and Russia

U.S. Secretary of state john kerry will be making his way to hear more about the russian deal that put that u.S. Military strike in syrian on hold. But a question tonight, can the u.S. Trust the russian promise and is it really possible to destroy one of the largest stock piles of chemical weapons in the world? Abc's chief global affairs correspondent martha raddatz takes us behind the promise. Reporter: The chemical sites are scattered across syria, containing the world's deadliest chemicals agents, 1,000 metric tons, of nerve gas, mustard gas, sarin which could easily wipe out the mideast. You could kill everyone in syria, and most people in the region. Reporter: To secure and DESTROY THEM, 100s OF UN Inspectors would have to be dispatched with syrian troops providing protection for the inspectors and the chemicals, all in the middle of a brutal civil war. This is the most daunting aspect of the challenge and that probably requires negotiation of a no fire zone around the storage depots. Reporter: The chemicals stored in barrels like these or loaded into weapons like these, would likely be consolidated at a few depots. Ideally a large "destruction" facility would be built inside syria or they could be moved somewhere like iraq. A destruction facility is essentially a giant, sealed oven, where chemicals would be incinerated by temperatures of more than 2,500 degrees reducing them to ash water vapor, carbon dioxide. Experts believe assad's chemical arsenal can be destroyed in two to four years, a herculean task during a war but the benefit far outweighs the burden. The mere act of turning them over into are international control takes the weapons away from assad. You've accomplished one of your strategic objectives. No matter how long it takes? No matter how long it takes. Reporter: No country that turned its weapons over has ever used chemical weapons again. But of course the first step is an agreement. Diane, tonight we have learned that the syrian opposition wants nothing to do with the russian proposal to secure those chemical weapons. They still want assad to be punished. And how does that complicate what's ahead? The u.S. Would certainly like the opposition groups on board, especially while they're trying to secure those weapons. They wouldn't want u.N. Teams coming under fire. I don't think this will halt the negotiation. It makes things more complicated and it already is complicated. Thank you so much martha

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